Abstract: A two-pass in situ oil shale retorting system uses two separate gas levels for withdrawing off gas from producing in situ oil shale retorts. During a first pass of retorting through an oil shale tract, spaced apart groups of in situ oil shale retorts are formed, leaving intervening barrier pillars of unfragmented formation between adjacent groups of retorts. During retorting, off gas from the retorts formed in the first pass is withdrawn to a first gas level drift system. Thereafter, during a second pass of retorting, intervening groups of in situ oil shale retorts are formed in the intervening barrier pillars between the groups of in situ retorts formed in the first pass. During retorting in the retorts formed in the second pass, off gas is withdrawn to a second gas level drift system that is formed at a different level and isolated from the first gas level drift system so that gas flow between the two gas levels is avoided.

Abstract: A ventilation and process air distribution system is provided for an in situ oil shale retort system which includes a production region having a cluster of retorts producing gaseous and liquid products and a retort preparation region where in situ retorts are being prepared for production. An underground air delivery drift system distributes process air to the production region and ventilation air to underground workings in the retort preparation region. A liquid collection drift system extends at or below the bottoms of the retorts in the production region and in the retort preparation region. The liquid collection drifts connect to an exhaust airway leading above ground and having an induction fan for inducing ventilation air to flow through the retort preparation region at a pressure lower than ambient air pressure above ground.

Abstract: A non-subsidence method for developing an in situ oil shale retort tract in a subterranean formation containing oil shale includes forming a number of spaced apart rows of in situ oil shale retorts, leaving intervening zones of unfragmented formation between adjacent rows of retorts for supporting the overburden loads without substantial subsidence. Each retort contains a fragmented permeable mass of formation particles containing oil shale. The retorts in each row are separated by gas barriers that provide support for the overburden load above each row of retorts. After retorting, a stabilizing material is introduced into the void spaces in the spent in situ oil shale retorts for increasing the compressive strength of the fragmented masses of spent oil shale particles in the spent in situ retorts. Thereafter, separate rows of in situ oil shale retorts are formed in corresponding intervening zones of unfragmented formation.

Abstract: A method of developing, mining and restoring a mining property having one or more mineral bearing rock seams is provided. Three-dimensional topographic control data, mineral bearing rock seam location data, water flow data, and overburden stratification and constituency data are collected and a topographic map of the mine property is prepared. An access road is located on the map to the mineral bearing rock seams and various environmental control facilities, topsoil storage areas and overburden disposal sites are identified and located on the map. Next, the mining operations are broken into sequential phases and placed on the topographic map. Mining of the seam material is then accomplished by sequential phases. After completing the first phase, each succeeding sequential phase is completed. During each succeeding sequential phase, a portion of the mine property in the preceeding phase is preferably restored.

Abstract: A gas seal is provided in an access drift excavated in a subterranean formation containing oil shale. The access drift is adjacent an in situ oil shale retort and is in gas communication with the fragmented permeable mass of formation particles containing oil shale formed in the in situ oil shale retort. The mass of formation particles extends into the access drift, forming a rubble pile of formation particles having a face approximately at the angle of repose of fragmented formation.The gas seal includes a temperature barrier which includes a layer of heat insulating material disposed on the face of the rubble pile of formation particles and additionally includes a gas barrier. The gas barrier is a gas-tight bulkhead installed across the access drift at a location in the access drift spaced apart from the temperature barrier.

Abstract: Improvements in the amount of ore receivable from a seam having an overburden and improvements in mine safety are achieved by strategically deploying inflated bladders for temporary overburden support and using certain bladders as forms for producing permanent support structures. An access wall is provided to an edge of the seam to be mined by forming a trench or tunnel; and, ore is mined by working into the access wall to produce a series of elongated, substantially parallel chambers. As each chamber is completed, its overburden is supported by inserting and inflating one or more bladders; and, caving of the access wall is prevented by installing a bladder at the mouth of the chamber. Because of the support, adjacent chambers may be quite close together, leaving only a thin rib of ore therebetween. When the work has progressed along the ore face, the inwardly disposed overburden supporting bladders in chambers remote from the newest excavation may be removed.

Abstract: A coal mining system is provided including a pneumatic separator having an air lock to separate the coal dust from the remainder of the coal aggregate in the system. A pneumatic suction means is provided to convey the dislodged coal aggregate from the mine face as it is mined by a mining machine. A duct carries the coal aggregate from the mining machine, past the separator where the coal aggregate remainder is transferred to an auger conveyor with the coal dust proceeding to a pollution control mechanism, such as a cyclone separator at a remote location outside the mine. A jet engine provides the suction for the system. A hopper is provided above the inlet to the auger conveyor providing the blocking concentration of coal to assure maintenance of the full vacuum in the pneumatic duct. A level control switch is operated by pivotal spade in the hopper and a similar switch is provided to sound an alarm when the hopper is filled to capacity.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of formation particles containing oil shale and has a production level drift in communication with a lower portion of the fragmented mass for withdrawing liquid and gaseous products of retorting during retorting of oil shale in the fragmented mass. The principal portion of the fragmented mass is spaced vertically above a lower production level portion having a generally T-shaped vertical cross section. The lower portion of the fragmented mass has a horizontal cross sectional area smaller than the horizontal cross sectional area of the upper principal portion of the fragmented mass above the production level.

Abstract: Mineable coal seams which are in proximity to an overlying or underlying coal seam are degasified in advance of and during mining by drilling a generally horizontal borehole in the overlying or underlying coal seam and producing gas therefrom.

Abstract: The invention concerns a method of surface mining along an elongated pit using a cross-pit conveyor for transferring selected excavated material, such as topsoil, directly across the pit while using a separate overburden excavator to transfer the remaining overburden. The method uses a cross-pit transporter which is supported solely on the working bank, includes a cantilevered conveyor which extends completely across the pit, and is slewable so it can periodically swing to a non-interfering position when passing the other excavator. The method allows the selective replacement of the different overburden materials in accordance with modern reclamation practice.

Abstract: An improved mining method for a surface mine has pairs of slurry and water pipes placed from a processing area on the surface to the floor of the mine beneath the mined out material, pairs of pipes (slurry and water) are spaced along the mining trench. A slurry haulage system is connected to the water and slurry pipes at the beginning of the mining operation. As the mining progresses and the haulage system reaches its maximum capabilities, it is disconnected and connected to the next set of pipes and the first set or pair of pipes is extended the width of the mined trench. The overburden is placed on top of the pipes as the mining progresses.

Abstract: An array of in situ oil shale retorts is formed in a development region in a subterranean formation containing oil shale. At least one void is excavated in each retort site, and remaining formation within each retort site is explosively expanded toward the void for forming a fragmented permeable mass of formation particles containing oil shale in each in situ retort. Overburden loads over an area of the development region are carried largely by the fragmented masses and partly by unfragmented partitions between retorts. Subsidence of overburden following explosive expansion is controlled at the boundary of the development region to avoid an abrupt change in the overburden load supported largely by the fragmented masses inside the boundary and the overburden load supported by unfragmented formation outside the boundary.

Abstract: Apparatus for the in-situ retorting of carbonaceous deposits includes a plurality of retorts connected to a common exhaust tunnel effectively free of broken shale into which products of the retorting are discharged. To allow simultaneous mining, rubblization and retorting of the in-situ retorts, the exhaust tunnel is provided with doorways between the retorts. Doors movable in the exhaust tunnel are adapted to seal against the doorways to prevent flow from retorts in which retorting is in progress to retorts under construction. A trench in the exhaust tunnel is provided for flow of liquid products produced in the retorting. A liquid seal under the doorways communicates with the trench to provide a passage for liquid flow past the doorways and to prevent upstream flow of gaseous products through the passage for the liquid flow.

Abstract: An underground mining method and apparatus which utilizes at least first and second spaced-apart shafts extending essentially downwardly into the earth and at least one lateral opening connecting the two shafts at a location below the earth's surface. An empty ore carrier is dropped into a first of said shafts and allowed to gravitationally fall towards the bottom of said shaft, its rate of descent being controlled by regulating the flow of air out of the bottom of said shaft. When the empty ore carrier reaches its stopping point in the first shaft, the carrier is transferred into the lateral opening filled with ore, then into a watertight compartment which is sealed and filled with water, and then into the second water-filled shaft. The ore-bearing carrier then floats to the earth's surface, is emptied, and returned empty to the first shaft for a repeat of the above procedure. Several carriers are kept in service at the same time.

Abstract: A method of reclaiming a highwall or sharp cliff like exposure mining site. The method includes the steps of placing a first series of directional charges at preselected locations in each of the auger, longwall or deep mine entry holes proximate the opening of the hole on the face of the highwall. Directional charges are positioned on the floor of the holes and pointed upward, obviating the need to drill charge placement holes. Such solid placement maximizes the explosive impact on the overburden above the charges thereby creating rubble from the overburden and tearing out sections of the in-situ material separating the holes. In one embodiment, a further series of charges is detonated at a preselected interval in time and depth from the detonation of the first series of directional charges to provide a synergistic explosive effect to accomplish the reclamation process.

Abstract: An improved procedure is disclosed for reclaiming land as it is surface mined; more particularly, reclamation of mined-out phosphate-containing land is disclosed where strata comprising a sandy component, a phosphate pebble component and a slime component are excavated, and the sandy component and the slime component are returned after extraction of the phosphate pebble component and dewatering by the dewatering system of the present invention. The volume of returned material is equal to or less than the volume of mined material, and the returned material forms a stable and agronomically sound soil. This result is obtained by accelerating dewatering of the slimes component of a specially treated backfill prior to and after deposition in the mined-out pit.

Abstract: The present method involves the initial mining of horizontally extending layers of oil-rich or "kerogen phase continuous" shale. The oil-rich shale is brought to the surface where it is retorted in above-ground retorts of one of the known types. The leaner oil shale which is still "in situ" is then explosively fragmented into the voids created when the oil-rich shale was mined, and oil is obtained as the fragmented shale is ignited, in accordance with known horizontal type modified in situ oil shale retorting techniques.

Abstract: A method for elevating extremely large blocks of earth by displacement with a slurry composed of water and locally excavated materials. The blocks are separated on lateral faces by variously drilling, jetting, fracturing, and kerf cutting operations. The blocks are separated at the lower end by notching and hydraulic fracturing. Block movement is started by injecting gelled fluid into the narrow separations.In one set of applications the high density slurry filling the side clearances is less dense than the block being elevated. In these cases the earth blocks are displaced upward by injecting fluid into the underside, and the non hydrostatic component of the displacement pressure is contained by the gel strength of the slurry filling the narrow side clearance. In a second set of applications the blocks being elevated contain a high percentage of coal, and slurry filling the side clearances exceeds the block density. The blocks are then displaced upward by hydrostatic pressure.

Abstract: The method of mining flat-dipping and sloping beds of a mineral with hydraulic excavation which includes dividing the bed being mined into levels and sublevels. The height of the sublevels is determined by the rock geology of the bed formation. The sublevels, in their turn, are subdivided into blocks, the width of each block being short of the limit length of the steady or self-supporting outreach of the cantilever of the rock of the main roof with the given pattern of cutting into the bed with the cutting drifts and holes defining the short working faces. The spacing of the blocks being worked in the upper and lower sublevels in the direction of strata is set to preclude inter-influence of the bearing rock pressure in the blocks where the stoping work is being done. The method enables the conduction of a stable excavation of the mineral over an extended front of stoping.

Abstract: A method for maximizing shale oil recovery from an underground oil shale formation which has previously been processed by in situ retorting such that there is provided in the formation a column of substantially intact oil shale intervening between adjacent spent retorts, which method includes the steps of back filling the spent retorts with an aqueous slurry of spent shale. The slurry is permitted to harden into a cement-like substance which stabilizes the spent retorts. Shale oil is then recovered from the intervening column of intact oil shale by retorting the column in situ, the stabilized spent retorts providing support for the newly developed retorts.

Abstract: A method of mining thick seam materials is performed by forming a pair of generally horizontal, vertically spaced, vertically aligned passes or drifts in one side of the thick seam. A number of contiguous vertical holes are drilled in the material from the lower to the upper drift to form a relatively large opening extending the length of the drifts. This large opening is then filled with low grade concrete to support the overburden and, after the concrete is set, a second pair of generally horizontal, vertically spaced, vertically aligned drifts are formed adjacent to the first mentioned drifts and the foregoing process is repeated. The above steps are continued until the entire seam of material has been removed.

Abstract: In the method of mining mineral deposits with hydraulic extraction a seam to be mined is divided into long pillars along the strike, and each pillar is subdivided with extraction workings and breakthroughs into benches defining short working faces, whereafter a single hydromonitor mounted in an extraction working is operated for stoping in the two adjacent benches, in the direction of the gravity flow of the slurry therealong. In accordance with the invention, boundary or run-around entries are driven, and communicated with the extraction workings via cut breakthroughs, whereafter these cut breakthroughs are expanded up to the sole of the seam, whereby at the stoping of the extraction cut in the two adjacent benches in the direction of the sloping of the extraction and boundary entries the main stream of the slurry is removed from the stope through the boundary working.

Abstract: A method of mining a seam of rigid hydrocarbonaceous containing mineral such as oil shale or coal whereby essentially complete recovery of the mineral deposit is possible. This method comprises the steps of apportioning the seam into one or more working horizons and extracting from about 15 to about 85 percent of the mineral in a horizon using a room and pillar mining technique. The void areas resulting from the above mining operation are then filled with concrete, which is formed from cement made from spent residue and aggregate comprised of additional spent material. After the void areas are filled the remaining mineral is removed and additional concrete is deposited. Subsequently, an adjacent horizon, either above or below the initial horizon, is excavated by repeating the above steps until essentially all of the mineral deposit is recovered.

Abstract: A safety wall treating method employed in the coal mining operation at the long wall face of a coal mine comprises shearing the long wall face leaving safety wall(s) at one or both side(s) of the face but shearing through the safety wall(s) at regular intervals to form intake or exhaust openings communicating with intake or exhaust tunnels.

Abstract: A method of mining a large underground seam of mineral, such as coal is described in which a first cylindrical shaft is drilled from the surface of the earth down to the mineral seam. A portion is enlarged at the base of the first shaft as a work room. A first radial shaft in the seam, out to a selected radius R, is drilled by conventional methods with the roofs supported by means such as hydraulic chocks which can be extended and moved selectively as the line of drilling progresses. When the first shaft is drilled, a continuous miner working on a short face method of mining is directly radially from the work room and is advanced outwardly until the width of the first radial shaft is such that the original wall of the first shaft has been cut away. The direction of the miner is then turned to be parallel to the first horizontal shaft and a short wall cutting advance is made to cut away the first wall of the first shaft and, in effect, drill a second shaft having a first wall spaced by the width of the cutter.

Abstract: An in-situ retort is formed in an oil shale deposit by a sublevel caving method in which the starting slot for the sublevel caving is at opposite ends of the retort on adjacent sublevels. Any zones of high permeability that are formed adjacent to the starting slots are limited in vertical extent to the vertical spacing of the sublevels and are spaced from the zones of high permeability in adjacent sublevels by the length of the retort. A source of channeling through the retort that is caused by the usual sublevel caving mining method is thereby eliminated.

Abstract: A carbonaceous deposit is retorted in an array of in-situ retorts comprising rectangular retorts arranged in rows. Adjacent rows of retorts are separated by an unbroken pillar extending the length of the rows. The bottoms of the in-situ retorts slope downwardly from a first side to the opposite side. An exhaust tunnel for the deliver of products from the retort located below the bottom of the retort extends longitudinally of the row with its outer wall approximately in alignment with, but not extending laterally beyond, the pillar to maintain the integrity of the pillar. The system is especially advantageous in the retorting of oil shale and is described in detail for that application.

Abstract: A group of spaced apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. At least one void is excavated in each retort site, and remaining formation within each retort site is explosively expanded toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in each retort. A vertically extending partition of substantially unfragmented formation forms a gas barrier between the fragmented masses in a pair of adjacent retorts. Such a gas barrier yields structurally but retains sufficient integrity to inhibit gas flow between the fragmented masses of adjacent retorts. Such a gas barrier is sufficiently thin that it independently supports substantially the same proportionate amount of load from overburden at elevations above the retorts as the fragmented masses on either side of the gas barrier.

Abstract: A method of extracting hydrocarbon from an underground strata, wherein the hydrocarbon has high in situ viscosity, by the steps of forming a vertical access hole from the earth's surface to a point below the strata, the diameter of the access hole being sufficient to permit passage of workmen and machinery, mining an elongated horizontal shaft from the vertical access hole under the strata, establishing at least one drilling station in the horizontal shaft, drilling upwardly from the drilling station a plurality of wells into the hydrocarbon strata, the wells being spaced apart and preferably drilled so as to be substantially vertical in the hydrocarbon strata, injecting a viscosity reducing agent into one or more of the wells to reduce hydrocarbon in the strata to free flowing liquid, withdrawing the free flowing hydrocarbon from the strata through one or more of the wells, and pumping the withdrawn hydrocarbon to the earth's surface.

Abstract: A coal mine ventilation system which insures proper ventilation near the working area. The basic system employs a mining machine on which is mounted a panel on a movable frame, a conventional line curtain fixed to the mine floor and roof and located adjacent to the panel, and an air control fluid spray system. Fluid sprays may be mounted on the machine on the opposite the panel to promote airflow towards the mining face. Additional sprays may be mounted on the machine panel to provide an effective barrier between that panel and the fixed line curtain.

Abstract: In-situ retorts of elongated rectangular shape in horizontal cross section are constructed in subsurface carbonaceous deposits in a plurality of parallel rows in each of which the retorts are arranged end-to-end. The rows are separated by unbroken pillars extending upwardly from rock that is not undermined or penetrated by retorts or tunnels. The ceilings of the retorts slope upwardly at an angle of at least 40.degree. with the horizontal to an apex or crown running longitudinally of the retorts to minimize the danger of roof collapse and provide a broadened pillar through which cross drifts opening into the crown of the retort extend for supplying combustion air. The crown of the ceiling is rounded to minimize concentration of the forces imposed by the overburden.

Abstract: An underground deposit of a carbonaceous material is retorted in an array of in-situ retorts arranged in a plurality of parallel rows. Each row of retorts is separated from adjacent rows by a pillar that extends unbroken for the length of the row. An apex drift extends longitudinally of each row and forms the crown of the retorts in that row. Combustion air for the retorting of the deposit in rubblized retorts in one row is supplied through the apex drift of an adjacent row. Delivery of combustion air into the crown of a retort for the retorting of the rubblized oil shale is through cross drifts from the apex drift of the adjacent row of retorts. Following combustion of the deposit in retorts in the first row, retorts are constructed and rubblized in a second row with the apex drift through which air had previously been supplied forming the crown of the retorts in the second row. Air for retorting deposit in the second row of retorts is delivered through a third apex drift.

Abstract: A strip mining technique wherein an active mining area is continuously moved across a mining ground. In one form of the invention, overburden is removed from a leading end of the active mining area and conveyed by a conveyor system located on a highwall of the mining area to a following end of that mining area. The conveyed overburden is dumped adjacent the active mining area following end to form a spoil bank which is landscaped and reclaimed. Another form of the invention includes a conveyor system located on the main bench.

Abstract: A strip mining technique wherein an active mining area is continuously moved across a mining ground. Overburden is removed from a leading end of the active mining area and conveyed by a conveyor system located on a high-wall of the mining area to a following end of that mining area. The conveyed overburden is dumped adjacent the active mining area following end to form a spoil bank which is landscaped and reclaimed.

Abstract: Liquid and gaseous products are recovered from oil shale in an in situ oil shale retort containing a fragmented permeable mass of particles containing oil shale by retorting oil shale in the fragmented mass to produce gaseous and liquid products. The liquid products are withdrawn from the retort to a first level in unfragmented formation below the elevation of the bottom boundary of the retort. Gaseous products are withdrawn from the retort to a second level below the elevation of the first level.

Abstract: Method of operating a quarry area comprises the steps of advancement of excavation such that a central trench is first provided for receiving overburden from adjacent strips to both sides of such trench. When the operation in the quarry is completed, a plurality of elongated spoil ridges are left with the valleys between the ridges providing solid ground for access roads to a further quarry area subsequently opened to one end of the depleted area. The method also facilitates the handling of overburden and transportation of the excavated rock in the existing quarry.

Abstract: A row of horizontally spaced apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row is formed by excavating at least a pair of upper and lower retort access drifts at elevations within the top and bottom boundaries of the retort sites. The access drifts extend through opposite side boundaries of a plurality of retorts in such row. Each retort is formed by excavating upper and lower horizontal voids at the levels of the upper and lower retort access drifts, respectively, such voids being excavated laterally from the access drift within the side boundaries of the retort sites. Each retort is formed by explosively expanding formation toward the upper and lower voids within the boundaries of the retort site to form a fragmented permeable mass of particles containing oil shale in each retort.

Abstract: Disclosed is a method for providing communication with a subterranean oil shale retort. This method can be used to provide a means of introducing fluids, such as a slurry of spent oil shale in water, into a retort. The method for providing lateral communication with a subterranean oil shale retort containing a rubblized retortable mass of oil shale, said retort being substantially surrounded by a mass of unmined formation comprises drilling at least one hole through the unmined formation adjacent to the retort; and providing communication between at least one of said holes and an adjacent retort; so that said drill hole can be used to communicate fluids to said retort. Fluids can be introduced into a spent retort which will form a supporting structure within said retort.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale. An open base of operation is excavated in the formation at an elevation above the fragmented mass to be formed, and an access drift is excavated to provide access to the bottom of the retort site. Formation is explosively expanded to form the fragmented mass between the access drift and an elevation spaced below the bottom of the base of operation, leaving a horizontal sill pillar of unfragmented formation between the top of the fragmented mass and the bottom of the base of operation. The sill pillar provides a safe base of operation above the fragmented mass after it is formed. The fragmented mass is formed by, among other steps, drilling blasting holes from the base of operation down through the sill pillar and then detonating explosive in such holes to form the fragmented mass of particles in the retort below the sill pillar.

Abstract: This invention relates to novel configurations of open pit mines and methods of mining in open pit operations in which the benches are established radially outward from a turning point to facilitate the use of a mobile crusher adjacent the benches in combination with a belt conveyor system that can carry crushed mined mineral materials directly from the mobile crusher and deliver them directly to the turning point area.

Abstract: An underground excavation method which reduces or eliminates the need for roof supports includes the cutting of one or more slots in a radial direction ahead of the advancing underground excavation. The plane of the slot is disposed perpendicular to the tangential stress that is expected around the prospective opening, so that the tangential stress is removed prior to the excavation of the opening, eliminating the potential damage to the boundary. The stress envelope finally formed after the excavation is radially expanded by the advanced slots, and can be made to stress-relieve the ground surrounding the excavation by controlling the length, number, and orientation of the advanced slots. The stress-relieved ground may be utilized as lining material by solidification with cement grouting or very limited anchor bolting.

Abstract: The invention relates to a method and apparatus for hydraulically mining friable carbonaceous material such as coal or other suitable materials wherein a feeder/breaker is placed in the entry with complete mining facilities mounted on this second machine including hydraulic monitors, one for cutting material from a seam or panel and, if desired, a second monitor for breaking and flushing the mined material in the form of a slurry for transport through the machine where it is mechanically broken and crushed to predetermined size and the solids/water slurry discharged into a flume for transport from the mine.

Abstract: There is provided a method for extraction of rock or ore according to the block caving principle comprising driving, at several levels, principally straight, parallel and horizontal drifts into the lower part of a block, choosing the distance between the drifts at each level so that remaining supporting pillars will cover at least 40% of the block area, undercutting the block from the drifts in such a way that the drift openings toward the undercut area and the drift coverings will be arranged in steps, the drift openings being utilized as draw-points for the caving material and the number of drift levels being chosen with regard to desired horizontal distance along the direction of the drift between the draw-points at adjacent levels.

Abstract: A method of mining a large underground seam of mineral such as coal is described in which a first cylindrical shaft is drilled from the surface of the earth down to the mineral seam. A portion is enlarged at the base of the first shaft as a work room. A first radial shaft out to a selected radius R is drilled by conventional methods with the roofs supported by means such as hydraulic chocks which can be extended and moved selectively as the line of drilling progresses. When the first shaft is drilled a continuous miner working on a short face method of mining is directed radially from the work room and is advanced outwardly until the width of the first radial shaft is such that the original wall of the first shaft has been cut away. The direction of the miner is then turned to be parallel to the first horizontal shaft and a short wall cutting advance is made to cut away the first wall of the first shaft and in effect drill a second shaft having a first wall spaced by the width of the cutter.

Abstract: An apparatus for cutting a deep slot, having a large depth to thickness ratio, in earth formations, which includes two main components, a motive means and a cutting assembly; the motive means, such as a crawler tractor, supports the projecting end of the cutting assembly, supplies a small portion of the driving force needed to advance the cutting assembly, and provides, through various connections, power, control functions, and the fluids required for operation of the cutting assembly; and the cutting assembly, extending the full depth of the slot along its advancing edge, includes an elongated support, a reciprocating cutter bar mounted on the leading edge of the support, a passage incorporated in the support for transmitting a fluid, generally a high gel strength clay paste, along the support and discharging the fluid in the interior of the slot, in a sufficient amount and under sufficient pressure to resist the earth pressure tending to close the slot and to provide a major portion of the force necessary t

Abstract: A shaft is formed from ground level downwardly to a subterranean seam of coal or other solids following preliminary survey procedures to locate the seam and establish its dimensions. A passage is cut radially into the coal seam and away from the shaft near the bottom thereof while coal cuttings are removed and delivered to ground level. The seam is then cut on an arcuate path centered on said shaft along the entire length of the radial passage while coal cuttings continue to be removed and delivered through the shaft to ground level. The mining apparatus is modular and comprises plural mining modules to be placed in the coal seam by a placement and advancing unit which is lowered in the shaft. A rotational driving unit is subsequently lowered in the shaft to drive coupled mining modules in unison through the coal seam on said arcuate path.

Abstract: In an auger mining system which forms an opening in the earth comprising a pair of axially aligned cylindrical holes and wherein the opening has a bottom, the system has a pair of side-by-side conveyors. Each auger conveyor has a shaft and a flight around the shaft which shafts are journaled through bearings at each end to a spacing member and where the spacing members are rigidly tied to each other by a longitudinal member having an underside. A supporting apparatus including a skid is attached to the auger pair and extending to the bottom of the opening. The skid may be attached either to the underside of the longitudinal member or to each of the bearings. If the skids are attached to the bearings, then skids which are on adjacent bearings of mating auger pairs are arcuately staggered to permit side-by-side positioning of the skids.

Abstract: A push-pull mining system comprising a pre-formed arrangement of personnel entry shafts, laterally extending service tunnels, flumes in the form of ditches extending substantially throughout each service tunnel, a holding tunnel at one side of each service tunnel and a chamber below the lowermost service tunnel at the end opposite to the holding tunnel for receiving a separation tank, a slurry mix tank, and an underground water reservoir. A mobile mining unit, comprising a mining machine at each end and carriers therebetween, is of substantially the same length as the holding tunnel. The mobile mining unit moves across the service tunnel to mine the opposing face and form a working tunnel which when finished is of the same length as the mobile unit. A mobile water station is mounted in the service tunnel and is connected to the mid-carrier which conveys the water to the mining machine at the end which is effective.

Abstract: In the mining of a thick underground mineral seam, parallel submain entries are developed at the top of the seam or at an upper level where a competent roof exists. Spaced apart parallel sets of panel entries are driven at right angles to these submain entries along a downwardly sloping path to the bottom of the seam. The entries are continued coincident with the bottom of the seam to any desired point at which their extremities are connected with bleeder entries so as to define a series of longwall panels. These panels are mined in retreat under the protection of advancing roof support structures so as to induce caving of overlying strata.

Abstract: Disclosed is a method for mining minerals at depths where strip and deep mining methods are not practical or economical. After site layout, a plurality of generally parallel-spaced, elongated trenches are formed to expose the mineral bed. Continuous mining equipment is used to mine the minerals from the base of the trench. A conveyor is disposed in each trench to convey the mined minerals to one end of the site to a collection conveyor. After the minerals are mined from the base of the trench, mining tunnels are formed to the opposite sides of and generally perpendicular to each trench and adjacent one end thereof. The tunnels are extended distances at least several times the width of the trench and thereby form longwall mining surfaces. Longwall mining equipment is disposed in each tunnel and the minerals are mined by advancing the longwall mining equipment in a direction parallel to the trench and toward its opposite end. As the longwall mining equipment advances, the overburden caves behind the equipment.